Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
int main(){
  int R,C,x,y,W=0;cin>>R>>C;
  pair<int,int>s=make_pair(0,0),g=make_pair(R-1,C-1);
  int N[R][C];char M[R][C];
  for(int i=0;i<R;i++)for(int j=0;j<C;j++){
    cin>>M[i][j];
    if(M[i][j]=='.')W++;
  }
  for(int i=0;i<R;i++)for(int j=0;j<C;j++)N[i][j]=W+1;
  N[0][0]=1;
  queue<pair<int,int>>X;
  X.push(s);
  while(X.front()!=g&&X.size()){
    x=X.front().first;y=X.front().second;
    if(x<R-1&&M[x+1][y]=='.'&&N[x+1][y]==W+1){X.push(make_pair(x+1,y));N[x+1][y]=N[x][y]+1;}
    if(x>0&&M[x-1][y]=='.'&&N[x-1][y]==W+1){X.push(make_pair(x-1,y));N[x-1][y]=N[x][y]+1;}
    if(y<C-1&&M[x][y+1]=='.'&&N[x][y+1]==W+1){X.push(make_pair(x,y+1));N[x][y+1]=N[x][y]+1;}
    if(y>0&&M[x][y-1]=='.'&&N[x][y-1]==W+1){X.push(make_pair(x,y-1));N[x][y-1]=N[x][y]+1;}
    X.pop();
  }
  cout<<W-N[R-1][C-1]<<endl;
}